The invention pertains to the field of animal husbandry and, in particular, egg laying cages for chickens utilizing grate floors.
The primary egg production in this country is produced by large batteries of laying cages vertically stacked relative to each other. The cages are of such size as to accommodate three or four chickens and the cage floors consist of an open grate through which the droppings pass, inclined to the horizontal whereby the eggs laid roll from the enclosure defined by the cage to an accessible portion of the floor. Such egg producing batteries may house between 10,000 and 50,000 hens.
As the laying cages are formed of welded wire, the weight of the chickens is supported upon the welded wire floor grate and the openings defined in the floor grate must be sufficient to permit the droppings to readily pass therethrough. It is common practice to now raise laying hens on wire grates from infancy and hens raised upon wire have a tendency to develop a foot formation wherein the toes bend and extend downwardly, often passing through the floor grate. Hens raised on the ground tend to develop feet which are substantially planar and the toes do not extend downwardly through a wire floor grate to the extent of hens raised from infancy on wire grates. As the hens' toes extend through the floor grate, occasionally the entire foot will extend through the grate opening and the spur, or other portion of the foot, will become caught in the floor grate. Such occurrence results in considerable excitement and commotion and the movement of the other hens in the cage often results in the death of the caught hen. Thus, it is not unusual for up to 10% of caged hens to die from such occurrences.
The floor grates of fowl cages have been the subject of a number of improvements and attention is directed to U.S. Pat. Nos. 2,766,723; 3,029,789; 3,757,741; 3,726,255 and 3,760,769.
Those improvements which have previously taken place have not overcome the two most important requirements for a laying cage subfloor. Namely, the floor must adequately support the hens to prevent their feet and spurs from being caught in the floor grate but the grate must be open enough to permit the droppings to readily pass therethrough. Grates of close mesh prevent the chickens' feet from being caught but such close mesh floor grates permit the droppings to catch and build up, causing serious sanitation problems resulting in dirty eggs and disease.